Field of the Invention
The invention relates to an arrangement for supplying a rail vehicle with electrical energy wherein the arrangement comprises at least two internal combustion engines to each of which one electrical machine for generating the electrical energy is assigned. The electrical machine is coupled mechanically with the assigned internal combustion engine so that when the electrical machine is in a generator operating mode it is driven by the internal combustion engine. The internal combustion engine and the electrical machine form an internal combustion engine-machine combination. The invention also relates to a method for operating the arrangement and a rail vehicle with the arrangement. Moreover, the invention relates to a method for manufacturing the arrangement and the rail vehicle.
The arrangement serves, more particularly, for supplying electrical traction motors in a rail vehicle with electrical energy and optionally also for supplying additional electrical auxiliary devices for the operation of the rail vehicle with electrical energy. The rail vehicle is, for example, a locomotive. The invention is not limited to that, however. In fact, the rail vehicle can, for example, also be a train unit.
Auxiliary devices as used herein are understood to mean devices which, though not producing traction directly may, more particularly, be necessarily required for the operation of the rail vehicle. Auxiliary devices can broadly be defined that they are supplied with electrical energy from the customarily available direct-current (DC) link by an own auxiliary device inverter or a plurality of own auxiliary device inverters. Examples of auxiliary devices are, e.g., fans and other cooling devices which cool the internal combustion engines, the traction motors and/or other devices (e.g., power converters) required for the operation of the rail vehicle. Moreover, also required for the operation of the rail vehicle is a brake assembly, and therefore components of the brake assembly such as air compressor also belong to the auxiliary devices. More examples of auxiliary devices are a fire extinguishing device of the rail vehicle, electronic devices for controlling the operation of the rail vehicle, battery charging devices, for the operation of the rail vehicle at least temporarily required heaters, e.g., windshield defroster heating, and/or lighting device in the driver's compartment. Optionally, differentiated from the auxiliary devices can be electrical devices provided merely for the comfort of passengers such as, for example, lamps in the compartments of the vehicle. In trains, such electrical devices are customarily supplied with electrical energy via the so called train bus bar.
The train bus bar is not connected with the DC link by the auxiliary device inverter or one of the auxiliary device inverters but by an inverter of its own.
It is prior art that the electrical energy generated by the electrical machines is fed into a DC link via at least one rectifier (hereinafter referred to as generator rectifier because the alternating current produced by the generator is rectified). Connected to the DC link are typically several inverters which, in turn, generate the alternating current on the required electrical voltage level or in the required electrical voltage range that is needed for the consumers and systems connected on the alternating voltage side. In addition to the inverters, provided on the latter's direct voltage side can be direct voltage converters and/or transformers on their alternating voltage side, for changing the voltage level. Other electrical converters can also be connected to the DC link, either directly or indirectly. Moreover, except the auxiliary devices named, other electrical consumers such as, e.g., electrical devices provided for the comfort of passengers such as light, air-conditioning and information systems, can also be supplied with electrical energy from the DC link, e.g., via an inverter other than the auxiliary devices required for the operation of the rail vehicle.
For example, connected to the DC link are: a plurality of traction motors of the rail vehicle via one or several traction inverters; a train power bus bar via an additional converter or directly; auxiliary devices required for the operation of the rail vehicle via an auxiliary device inverter. Besides, additional converters can be connected to the DC link, e.g., for the purpose of converting into heat excess energy fed into the DC link during the braking of the rail vehicle. An example of such an arrangement is characterized in WO 2009/077184 A1.
The invention relates to the case in which more than one internal combustion engine is provided and in each case at least one electrical machine is coupled to the internal combustion engine. It is therefore possible that only a part of the electrical machines provided generates electrical energy whereas, at the same time, another part of the electrical machines operates as motor, more particularly, to power the associated internal combustion engine in idle mode. The advantage of that is that the fuel supply of the internal combustion engine can be stopped. Alternately, it is also possible that at least one of the internal combustion engines runs merely at low speed and therefore the associated electrical machine generates or electrical machines generate only a low electrical output which does not or does not significantly contribute to the electrical output that is fed into the DC link.
Basically, a difference is to be made between the following operating states of an internal combustion engine:                The moving parts of the internal combustion engine do not move. This state is referred to as turned-off state. In that state, no fuel is injected into the combustion spaces of the engine.        The moving parts of the internal combustion engine move by the power of the electrical machine that is coupled to the engine. In that state also, no fuel is injected into the combustion spaces of the engine. That state is referred to as deceleration fuel cut-off.        The internal combustion engine produces mechanical power. Consequently, the electrical machine coupled to the engine is driven and generates electrical energy. In that state, fuel is injected into the combustion spaces to produce mechanical power.        
More particularly, the invention relates to the case in which temporarily at least one of the internal combustion engines is turned off.
A plurality of internal combustion engine-machine combinations offers advantages in the part-load operation mode of the rail vehicle, i.e., in an operation in which not the maximum possible electrical power is needed. In part-load operation mode, the mechanical power of merely a part of the internal combustion engine suffices to provide the required electrical power. In addition to a reduction of the fuel consumption of the internal combustion engine, the noise pollution of the environment in the part load operation mode is also lower. For example, four internal combustion engine-machine combinations can be provided, in which preferably each combination can be operated independently of the other combinations either in idle mode or at the optimal power point. Optionally more than two operating modes can be set for each combination, e.g., in addition to the two operating modes mentioned, an operating mode with medium power of the electrical machine operating as generator.
More particularly, for the other possible features of an arrangement with several internal combustion engine-machine combinations, reference is made here to the international patent application number PCT/EP 2012/052705 filed on Feb. 16, 2012. More particularly, the entire content of that application is hereby included by reference.
Description of Related Art
It is prior art to pre-heat the internal combustion engines before they are started. More particularly, in practice, cooling liquid is provided by a cooling circulation system for cooling the internal combustion engine wherein the cooling liquid is preheated if necessary. The energy required for preheating can be obtained particularly from converting electrical energy into heat, by exothermal chemical processes (more particularly, the combustion of fossil fuel) and/or by the release of stored thermal energy (optionally by discharging a latent heat accumulator).
Disclosed in WO 2008/089571 A1 is a method for controlling a required total output power of a vehicle that comprises a plurality of energy sources. These energy sources provide electrical power to a common DC link. A number of energy sources to be used is selected, and that according to a scheme to supply power to the DC link. The energy sources are activated according to the scheme. If the power output of one of the energy sources is different from a target power output, control parameters of the energy source are adapted to correct the difference. In the concrete embodiment of FIG. 17 of the said publication, it is determined at first whether a warm internal combustion engine is available. In any case, in selecting the internal combustion, it is considered which internal combustion engine had been used more often than others in the past so that the use is balanced more or less. Besides, the selection can be at random or in a regular cycle. When no warm internal combustion engine is available, the selected internal combustion engine is preheated.